Textiles companies could face potential fines of millions of pounds if found guilty of letting their employees go deaf through work.
The Nottinghamshire and Derbyshire Industrial Deafness Litigation involves about 1,500 former textiles workers who claim to suffer from noise-induced hearing loss from working at local mills.
They say their employers let them work close to noisy machinery without providing ear protection, despite knowing it would risk damaging their hearing.
Ten test cases are being brought against companies including Coats Viyella, Courtaulds and Warwick Fabrics in a group action.
If the judge rules in favour of the workers it could pave the way for a government-assisted compensation scheme, similar to the Department of Trade and Industry scheme currently in place for miners suffering with breathing difficulties or vibration white finger.